RowUpdatingEventHandler and RowUpdatedEventHandler sample using ODP.NET

Table of Contents

• Objective of the Sample Application
• Overview of the Sample Application
• User Notes with Screen Shots
• Required Software
• Extracting the Sample
• Database Setup
• Preparing and Running the sample
• Steps in the sample
• Description of Sample Files

The purpose of this sample application is to demonstrate how one can trap the OracleRowUpdatingEvent and OracleRowUpdatedEvent using VB.NET.

Oracle Data Provider for .NET (ODP.NET) is an implementation of a data provider for the Oracle database. ODP.NET uses Oracle native APIs to offer fast and reliable access to Oracle data and features from any .NET application. ODP.NET is provided in Oracle.ManagedDataAccesss.dll assembly and provides two namespaces :

• The Oracle.ManagedDataAccess.Client namespace contains ODP.NET classes.
• The Oracle.ManagedDataAccess.Types namespace contains the ODP.NET Types.
  

Event handling is the mechanism by which .NET components register themselves with event generators and then get notified with the help of a callback when the event is fired. ODP.NET too allows users to register event handlers and get notified when the event of particular interest occurs. In this application we demonstrate how one can trap the OracleDataAdapter.RowUpdating and OracleDataAdapter.RowUpdated events. OracleDataAdapter.RowUpdating event is fired before a row is updated. OracleDataAdapter.RowUpdated event is fired after a row is updated. This allows applications to process this event and initiate appropriate action.

 

User Notes with Screen Shots

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When this sample application is run, users should supply a username, password and connect string to connect to a database. The application creates the required table to set up this application. By default, both RowUpdating and RowUpdated event handlers are enabled. Users can use the radio buttons to enable, disable the event handlers. They must click the "Apply" button to carry out actual eventHandler registration or de-registration. If the event handler is enabled and country table is updated then corresponding event handler code is executed. Code inside the eventHandler function (Subroutine) prints a line in the status window indicating that the function had been invoked.

Figure 1.1: Screen shot of the Main Screen

• VB.NET installed with Visual Studio 2005/2008/2010/2012.

• Oracle11g Database or higher running SQL*Net TCP/IP listener (can be downloaded here )

• Oracle Data Provider for .NET (ODP.NET) (can be downloaded here )

Unzip RowUpdateEventHandler.zip using Winzip or command utility to your convenient directory referred to as <Extract_Dir>. Extraction of the zip file results in the creation of 'RowUpdateEventHandler' directory.  Refer Description of Sample Files section for more details.     

No special database setup is required. When this application starts it creates the required table 'COUNTRYTAB' and inserts necessary data. You must ensure that the database user has necessary privileges to drop,create and update tables.

1. Open RowUpdateEventHandler.sln using Visual Studio .NET from <Extract_Dir>\RowUpdateEventHandler\src folder. 

2. Ensure that the following .NET Component References have been added to RowUpdateEventHandler project: 
          Oracle.ManagedDataAccess. 
          System,
          System.Data, 
          System.Drawing, 
          System.Windows.Forms, 
          System.XML,
         

To add the reference to above .NET Components 
a)Go to Menu ->View-> Solution Explorer. 
b)Right click on RowUpdateEventHandler project, choose 'Add Reference'. 
c)Choose the above .NET Components from the list displayed. 
d)Click 'Select', then OK. 
e) The chosen .NET component gets added to the project. 

4. Build and run the sample.

1. When the Main form of the application appears as shown in figure 1.1 enter the username , password and connect string as per your database setting and press "Connect" button.

2. You may update Language or Currency columns. Other columns are not updatable.

2. To update the rows in the DataGrid press "Update" button. You may enable or disable the eventhandlers by using radio buttons but you must press "Apply" button to carry out actual handler registration or de-registration process.

Note: The database user used to execute this application must have necessary privileges to create, delete and modify tables.

Following is the directory structure of the RowUpdateEventHandler.zip :